1. The problem statement, all variables and given/known data Hi, got my HW back from prof. There were a few problems... I want to understand these before the test. Show that r(t) = (at^2)/2 + vt + r lies in a plane and that if a and v are not parallel, then r(t) traces out a parabola. Note a, v, and r are constant vectors here (i.e. acceleration, velocity, and position and t is time) 2. Relevant equations 1. y = Ax + Bx^2 (prof said to show this) 3. The attempt at a solution I wasn't sure about this. I put that since v(r) = dr/dt = at + v, there is no 3rd direction in which particle will move (since r disappears). Also, we can pass a plane through any two vectors... In regards to showing y = Ax + Bx^2, is it as simple as letting x = t and y = r(t) -r? This would make it fit the form since A = a/2 = constant, right? Or do I have to do something by decompose these vectors such as x(t) = (axt^2)/2 + vxt + x, y(t) = (ayt^2)/2 + vyt + y, etc. I'm just not sure what prof. wants??? Thanks!